The objective of this project is to examine the effects of chronic administration of delta-9-tetrahydrocannabinol (THC) upon mouse eggs and embryos. The study is designed to imitate the prolonged use of THC by sexually immature and adolescent girls. Ova, unlike sperms, are incapable of regeneration. Therefore, any genetic damages inflicted by THC on these cells should be permanent and reflect in the fertilized eggs and embryos. THC will be administered daily to sexually immature female mice until sexual maturity. Superovulation will, then, be induced. The treated mice will be mated with untreated males. Fertilized eggs and embryos will be obtained at various stages of development. These eggs and embryos will be examined for their morphology, karyotypes, chromosomal breakages, segregational errors of chromosomes, and sister chromatid exchanges. In other group of mice, superovulation will not be induced until 6 weeks after the last dose of THC. Possible recovery from the effects of THC will be examined in these animals. In the third group of female mice, THC labelled with H3 will be administered, and uptake of THC by the ova will be determined using an autoradiographic technique. Each set of experiments will be compared statistically with appropriate controls.